nds32: Signal handling support

This patch adds support for signal handling.
Signed-off-by: NVincent Chen <vincentc@andestech.com>
Signed-off-by: NGreentime Hu <greentime@andestech.com>

arch/nds32/include/uapi/asm/sigcontext.h

+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2005-2017 Andes Technology Corporation
+
+#ifndef _ASMNDS32_SIGCONTEXT_H
+#define _ASMNDS32_SIGCONTEXT_H
+
+/*
+ * Signal context structure - contains all info to do with the state
+ * before the signal handler was invoked.  Note: only add new entries
+ * to the end of the structure.
+ */
+
+struct zol_struct {
+	unsigned long nds32_lc;	/* $LC */
+	unsigned long nds32_le;	/* $LE */
+	unsigned long nds32_lb;	/* $LB */
+};
+
+struct sigcontext {
+	unsigned long trap_no;
+	unsigned long error_code;
+	unsigned long oldmask;
+	unsigned long nds32_r0;
+	unsigned long nds32_r1;
+	unsigned long nds32_r2;
+	unsigned long nds32_r3;
+	unsigned long nds32_r4;
+	unsigned long nds32_r5;
+	unsigned long nds32_r6;
+	unsigned long nds32_r7;
+	unsigned long nds32_r8;
+	unsigned long nds32_r9;
+	unsigned long nds32_r10;
+	unsigned long nds32_r11;
+	unsigned long nds32_r12;
+	unsigned long nds32_r13;
+	unsigned long nds32_r14;
+	unsigned long nds32_r15;
+	unsigned long nds32_r16;
+	unsigned long nds32_r17;
+	unsigned long nds32_r18;
+	unsigned long nds32_r19;
+	unsigned long nds32_r20;
+	unsigned long nds32_r21;
+	unsigned long nds32_r22;
+	unsigned long nds32_r23;
+	unsigned long nds32_r24;
+	unsigned long nds32_r25;
+	unsigned long nds32_fp;	/* $r28 */
+	unsigned long nds32_gp;	/* $r29 */
+	unsigned long nds32_lp;	/* $r30 */
+	unsigned long nds32_sp;	/* $r31 */
+	unsigned long nds32_ipc;
+	unsigned long fault_address;
+	unsigned long used_math_flag;
+	/* FPU Registers */
+	struct zol_struct zol;
+};
+
+#endif

arch/nds32/kernel/signal.c

+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2005-2017 Andes Technology Corporation
+
+#include <linux/errno.h>
+#include <linux/signal.h>
+#include <linux/ptrace.h>
+#include <linux/personality.h>
+#include <linux/freezer.h>
+#include <linux/tracehook.h>
+#include <linux/uaccess.h>
+
+#include <asm/cacheflush.h>
+#include <asm/ucontext.h>
+#include <asm/unistd.h>
+
+#include <asm/ptrace.h>
+#include <asm/vdso.h>
+
+struct rt_sigframe {
+	struct siginfo info;
+	struct ucontext uc;
+};
+
+static int restore_sigframe(struct pt_regs *regs,
+			    struct rt_sigframe __user * sf)
+{
+	sigset_t set;
+	int err;
+
+	err = __copy_from_user(&set, &sf->uc.uc_sigmask, sizeof(set));
+	if (err == 0) {
+		set_current_blocked(&set);
+	}
+
+	__get_user_error(regs->uregs[0], &sf->uc.uc_mcontext.nds32_r0, err);
+	__get_user_error(regs->uregs[1], &sf->uc.uc_mcontext.nds32_r1, err);
+	__get_user_error(regs->uregs[2], &sf->uc.uc_mcontext.nds32_r2, err);
+	__get_user_error(regs->uregs[3], &sf->uc.uc_mcontext.nds32_r3, err);
+	__get_user_error(regs->uregs[4], &sf->uc.uc_mcontext.nds32_r4, err);
+	__get_user_error(regs->uregs[5], &sf->uc.uc_mcontext.nds32_r5, err);
+	__get_user_error(regs->uregs[6], &sf->uc.uc_mcontext.nds32_r6, err);
+	__get_user_error(regs->uregs[7], &sf->uc.uc_mcontext.nds32_r7, err);
+	__get_user_error(regs->uregs[8], &sf->uc.uc_mcontext.nds32_r8, err);
+	__get_user_error(regs->uregs[9], &sf->uc.uc_mcontext.nds32_r9, err);
+	__get_user_error(regs->uregs[10], &sf->uc.uc_mcontext.nds32_r10, err);
+	__get_user_error(regs->uregs[11], &sf->uc.uc_mcontext.nds32_r11, err);
+	__get_user_error(regs->uregs[12], &sf->uc.uc_mcontext.nds32_r12, err);
+	__get_user_error(regs->uregs[13], &sf->uc.uc_mcontext.nds32_r13, err);
+	__get_user_error(regs->uregs[14], &sf->uc.uc_mcontext.nds32_r14, err);
+	__get_user_error(regs->uregs[15], &sf->uc.uc_mcontext.nds32_r15, err);
+	__get_user_error(regs->uregs[16], &sf->uc.uc_mcontext.nds32_r16, err);
+	__get_user_error(regs->uregs[17], &sf->uc.uc_mcontext.nds32_r17, err);
+	__get_user_error(regs->uregs[18], &sf->uc.uc_mcontext.nds32_r18, err);
+	__get_user_error(regs->uregs[19], &sf->uc.uc_mcontext.nds32_r19, err);
+	__get_user_error(regs->uregs[20], &sf->uc.uc_mcontext.nds32_r20, err);
+	__get_user_error(regs->uregs[21], &sf->uc.uc_mcontext.nds32_r21, err);
+	__get_user_error(regs->uregs[22], &sf->uc.uc_mcontext.nds32_r22, err);
+	__get_user_error(regs->uregs[23], &sf->uc.uc_mcontext.nds32_r23, err);
+	__get_user_error(regs->uregs[24], &sf->uc.uc_mcontext.nds32_r24, err);
+	__get_user_error(regs->uregs[25], &sf->uc.uc_mcontext.nds32_r25, err);
+
+	__get_user_error(regs->fp, &sf->uc.uc_mcontext.nds32_fp, err);
+	__get_user_error(regs->gp, &sf->uc.uc_mcontext.nds32_gp, err);
+	__get_user_error(regs->lp, &sf->uc.uc_mcontext.nds32_lp, err);
+	__get_user_error(regs->sp, &sf->uc.uc_mcontext.nds32_sp, err);
+	__get_user_error(regs->ipc, &sf->uc.uc_mcontext.nds32_ipc, err);
+#if defined(CONFIG_HWZOL)
+	__get_user_error(regs->lc, &sf->uc.uc_mcontext.zol.nds32_lc, err);
+	__get_user_error(regs->le, &sf->uc.uc_mcontext.zol.nds32_le, err);
+	__get_user_error(regs->lb, &sf->uc.uc_mcontext.zol.nds32_lb, err);
+#endif
+
+	/*
+	 * Avoid sys_rt_sigreturn() restarting.
+	 */
+	forget_syscall(regs);
+	return err;
+}
+
+asmlinkage long sys_rt_sigreturn(struct pt_regs *regs)
+{
+	struct rt_sigframe __user *frame;
+
+	/* Always make any pending restarted system calls return -EINTR */
+	current->restart_block.fn = do_no_restart_syscall;
+
+	/*
+	 * Since we stacked the signal on a 64-bit boundary,
+	 * then 'sp' should be two-word aligned here.  If it's
+	 * not, then the user is trying to mess with us.
+	 */
+	if (regs->sp & 7)
+		goto badframe;
+
+	frame = (struct rt_sigframe __user *)regs->sp;
+
+	if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
+		goto badframe;
+
+	if (restore_sigframe(regs, frame))
+		goto badframe;
+
+	if (restore_altstack(&frame->uc.uc_stack))
+		goto badframe;
+
+	return regs->uregs[0];
+
+badframe:
+	force_sig(SIGSEGV, current);
+	return 0;
+}
+
+static int
+setup_sigframe(struct rt_sigframe __user * sf, struct pt_regs *regs,
+	       sigset_t * set)
+{
+	int err = 0;
+
+	__put_user_error(regs->uregs[0], &sf->uc.uc_mcontext.nds32_r0, err);
+	__put_user_error(regs->uregs[1], &sf->uc.uc_mcontext.nds32_r1, err);
+	__put_user_error(regs->uregs[2], &sf->uc.uc_mcontext.nds32_r2, err);
+	__put_user_error(regs->uregs[3], &sf->uc.uc_mcontext.nds32_r3, err);
+	__put_user_error(regs->uregs[4], &sf->uc.uc_mcontext.nds32_r4, err);
+	__put_user_error(regs->uregs[5], &sf->uc.uc_mcontext.nds32_r5, err);
+	__put_user_error(regs->uregs[6], &sf->uc.uc_mcontext.nds32_r6, err);
+	__put_user_error(regs->uregs[7], &sf->uc.uc_mcontext.nds32_r7, err);
+	__put_user_error(regs->uregs[8], &sf->uc.uc_mcontext.nds32_r8, err);
+	__put_user_error(regs->uregs[9], &sf->uc.uc_mcontext.nds32_r9, err);
+	__put_user_error(regs->uregs[10], &sf->uc.uc_mcontext.nds32_r10, err);
+	__put_user_error(regs->uregs[11], &sf->uc.uc_mcontext.nds32_r11, err);
+	__put_user_error(regs->uregs[12], &sf->uc.uc_mcontext.nds32_r12, err);
+	__put_user_error(regs->uregs[13], &sf->uc.uc_mcontext.nds32_r13, err);
+	__put_user_error(regs->uregs[14], &sf->uc.uc_mcontext.nds32_r14, err);
+	__put_user_error(regs->uregs[15], &sf->uc.uc_mcontext.nds32_r15, err);
+	__put_user_error(regs->uregs[16], &sf->uc.uc_mcontext.nds32_r16, err);
+	__put_user_error(regs->uregs[17], &sf->uc.uc_mcontext.nds32_r17, err);
+	__put_user_error(regs->uregs[18], &sf->uc.uc_mcontext.nds32_r18, err);
+	__put_user_error(regs->uregs[19], &sf->uc.uc_mcontext.nds32_r19, err);
+	__put_user_error(regs->uregs[20], &sf->uc.uc_mcontext.nds32_r20, err);
+
+	__put_user_error(regs->uregs[21], &sf->uc.uc_mcontext.nds32_r21, err);
+	__put_user_error(regs->uregs[22], &sf->uc.uc_mcontext.nds32_r22, err);
+	__put_user_error(regs->uregs[23], &sf->uc.uc_mcontext.nds32_r23, err);
+	__put_user_error(regs->uregs[24], &sf->uc.uc_mcontext.nds32_r24, err);
+	__put_user_error(regs->uregs[25], &sf->uc.uc_mcontext.nds32_r25, err);
+	__put_user_error(regs->fp, &sf->uc.uc_mcontext.nds32_fp, err);
+	__put_user_error(regs->gp, &sf->uc.uc_mcontext.nds32_gp, err);
+	__put_user_error(regs->lp, &sf->uc.uc_mcontext.nds32_lp, err);
+	__put_user_error(regs->sp, &sf->uc.uc_mcontext.nds32_sp, err);
+	__put_user_error(regs->ipc, &sf->uc.uc_mcontext.nds32_ipc, err);
+#if defined(CONFIG_HWZOL)
+	__put_user_error(regs->lc, &sf->uc.uc_mcontext.zol.nds32_lc, err);
+	__put_user_error(regs->le, &sf->uc.uc_mcontext.zol.nds32_le, err);
+	__put_user_error(regs->lb, &sf->uc.uc_mcontext.zol.nds32_lb, err);
+#endif
+
+	__put_user_error(current->thread.trap_no, &sf->uc.uc_mcontext.trap_no,
+			 err);
+	__put_user_error(current->thread.error_code,
+			 &sf->uc.uc_mcontext.error_code, err);
+	__put_user_error(current->thread.address,
+			 &sf->uc.uc_mcontext.fault_address, err);
+	__put_user_error(set->sig[0], &sf->uc.uc_mcontext.oldmask, err);
+
+	err |= __copy_to_user(&sf->uc.uc_sigmask, set, sizeof(*set));
+
+	return err;
+}
+
+static inline void __user *get_sigframe(struct ksignal *ksig,
+					struct pt_regs *regs, int framesize)
+{
+	unsigned long sp;
+
+	/* Default to using normal stack */
+	sp = regs->sp;
+
+	/*
+	 * If we are on the alternate signal stack and would overflow it, don't.
+	 * Return an always-bogus address instead so we will die with SIGSEGV.
+	 */
+	if (on_sig_stack(sp) && !likely(on_sig_stack(sp - framesize)))
+		return (void __user __force *)(-1UL);
+
+	/* This is the X/Open sanctioned signal stack switching. */
+	sp = (sigsp(sp, ksig) - framesize);
+
+	/*
+	 * nds32 mandates 8-byte alignment
+	 */
+	sp &= ~0x7UL;
+
+	return (void __user *)sp;
+}
+
+static int
+setup_return(struct pt_regs *regs, struct ksignal *ksig, void __user * frame)
+{
+	unsigned long handler = (unsigned long)ksig->ka.sa.sa_handler;
+	unsigned long retcode;
+
+	retcode = VDSO_SYMBOL(current->mm->context.vdso, rt_sigtramp);
+	regs->uregs[0] = ksig->sig;
+	regs->sp = (unsigned long)frame;
+	regs->lp = retcode;
+	regs->ipc = handler;
+
+	return 0;
+}
+
+static int
+setup_rt_frame(struct ksignal *ksig, sigset_t * set, struct pt_regs *regs)
+{
+	struct rt_sigframe __user *frame =
+	    get_sigframe(ksig, regs, sizeof(*frame));
+	int err = 0;
+
+	if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
+		return -EFAULT;
+
+	__put_user_error(0, &frame->uc.uc_flags, err);
+	__put_user_error(NULL, &frame->uc.uc_link, err);
+
+	err |= __save_altstack(&frame->uc.uc_stack, regs->sp);
+	err |= setup_sigframe(frame, regs, set);
+	if (err == 0) {
+		setup_return(regs, ksig, frame);
+		if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
+			err |= copy_siginfo_to_user(&frame->info, &ksig->info);
+			regs->uregs[1] = (unsigned long)&frame->info;
+			regs->uregs[2] = (unsigned long)&frame->uc;
+		}
+	}
+	return err;
+}
+
+/*
+ * OK, we're invoking a handler
+ */
+static void handle_signal(struct ksignal *ksig, struct pt_regs *regs)
+{
+	int ret;
+	sigset_t *oldset = sigmask_to_save();
+
+	if (in_syscall(regs)) {
+		/* Avoid additional syscall restarting via ret_slow_syscall. */
+		forget_syscall(regs);
+
+		switch (regs->uregs[0]) {
+		case -ERESTART_RESTARTBLOCK:
+		case -ERESTARTNOHAND:
+			regs->uregs[0] = -EINTR;
+			break;
+		case -ERESTARTSYS:
+			if (!(ksig->ka.sa.sa_flags & SA_RESTART)) {
+				regs->uregs[0] = -EINTR;
+				break;
+			}
+		case -ERESTARTNOINTR:
+			regs->uregs[0] = regs->orig_r0;
+			regs->ipc -= 4;
+			break;
+		}
+	}
+	/*
+	 * Set up the stack frame
+	 */
+	ret = setup_rt_frame(ksig, oldset, regs);
+
+	signal_setup_done(ret, ksig, 0);
+}
+
+/*
+ * Note that 'init' is a special process: it doesn't get signals it doesn't
+ * want to handle. Thus you cannot kill init even with a SIGKILL even by
+ * mistake.
+ *
+ * Note that we go through the signals twice: once to check the signals that
+ * the kernel can handle, and then we build all the user-level signal handling
+ * stack-frames in one go after that.
+ */
+static void do_signal(struct pt_regs *regs)
+{
+	struct ksignal ksig;
+
+	if (get_signal(&ksig)) {
+		handle_signal(&ksig, regs);
+		return;
+	}
+
+	/*
+	 * If we were from a system call, check for system call restarting...
+	 */
+	if (in_syscall(regs)) {
+		/* Restart the system call - no handlers present */
+
+		/* Avoid additional syscall restarting via ret_slow_syscall. */
+		forget_syscall(regs);
+
+		switch (regs->uregs[0]) {
+		case -ERESTART_RESTARTBLOCK:
+			regs->uregs[15] = __NR_restart_syscall;
+		case -ERESTARTNOHAND:
+		case -ERESTARTSYS:
+		case -ERESTARTNOINTR:
+			regs->uregs[0] = regs->orig_r0;
+			regs->ipc -= 0x4;
+			break;
+		}
+	}
+	restore_saved_sigmask();
+}
+
+asmlinkage void
+do_notify_resume(struct pt_regs *regs, unsigned int thread_flags)
+{
+	if (thread_flags & _TIF_SIGPENDING)
+		do_signal(regs);
+
+	if (thread_flags & _TIF_NOTIFY_RESUME) {
+		clear_thread_flag(TIF_NOTIFY_RESUME);
+		tracehook_notify_resume(regs);
+	}
+}